Ceramic fiber insulation materials are used in numerous applications (e.g. aerospace, fire protection, and military) for their stability and performance in extreme environments. However, the thermal properties of these materials have not been thoroughly characterized for many of the conditions that they will be exposed to, such as high temperatures, pressures, and alternate gaseous atmospheres. The resulting uncertainty in the material properties can complicate the design of systems using these materials. In this study, the thermal conductivity of two ceramic fiber insulations, Fiberfrax T-30LR laminate and 970-H paper, was measured as a function of atmospheric temperature and compression in an air environment using the transient plane source technique. Furthermore, a model is introduced to account for changes in thermal conductivity with temperature, compression, and ambient gas. The model was tuned to the collected experimental data and results are compared. The tuned model is also compared to published data sets taken in argon, helium, and hydrogen environments and agreement is discussed.
The present study results are focused on laboratory testing of surrogate materials representing Waste Isolation Pilot Plant (WIPP) waste. The surrogate wastes correspond to a conservative estimate of the containers and transuranic waste materials emplaced at the WIPP. Testing consists of hydrostatic, triaxial, and uniaxial tests performed on surrogate waste recipes based on those previously developed by Hansen et al. (1997). These recipes represent actual waste by weight percent of each constituent and total density. Testing was performed on full-scale and 1/4-scale containers. Axial, lateral, and volumetric strain and axial and lateral stress measurements were made. Unique testing techniques were developed during the course of the experimental program. The first involves the use of a spirometer or precision flow meter to measure sample volumetric strain under the various stress conditions. Since the manner in which the waste containers deformed when compressed was not even, the volumetric and axial strains were used to determine the lateral strains. The second technique involved the development of unique coating procedures that also acted as jackets during hydrostatic, triaxial, and full-scale uniaxial testing; 1/4-scale uniaxial tests were not coated but wrapped with clay to maintain an airtight seal for volumetric strain measurement. During all testing methods, the coatings allowed the use of either a spirometer or precision flow meter to estimate the amount of air driven from the container as it crushed down since the jacket adhered to the container and yet was flexible enough to remain airtight during deformation.
We are developing computational models to elucidate the expansion and dynamic filling process of a polyurethane foam, PMDI. The polyurethane of interest is chemically blown, where carbon dioxide is produced via the reaction of water, the blowing agent, and isocyanate. The isocyanate also reacts with polyol in a competing reaction, which produces the polymer. Here we detail the experiments needed to populate a processing model and provide parameters for the model based on these experiments. The model entails solving the conservation equations, including the equations of motion, an energy balance, and two rate equations for the polymerization and foaming reactions, following a simplified mathematical formalism that decouples these two reactions. Parameters for the polymerization kinetics model are reported based on infrared spectrophotometry. Parameters describing the gas generating reaction are reported based on measurements of volume, temperature and pressure evolution with time. A foam rheology model is proposed and parameters determined through steady-shear and oscillatory tests. Heat of reaction and heat capacity are determined through differential scanning calorimetry. Thermal conductivity of the foam as a function of density is measured using a transient method based on the theory of the transient plane source technique. Finally, density variations of the resulting solid foam in several simple geometries are directly measured by sectioning and sampling mass, as well as through x-ray computed tomography. These density measurements will be useful for model validation once the complete model is implemented in an engineering code.